The present invention relates to a capacitive dynamic quantity sensor.
For example, a capacitive semiconductor acceleration sensor 27, or sensor chip 27, shown in FIG. 4A is such a capacitive dynamic quantity sensor. As shown in FIG. 4A, in the sensor chip 27, a weight 11 is supported by movable unit anchors 14 through springs 12, which are expandable and shrinkable. First and second comb-tooth-like movable electrodes 10a, 10b are integrated with the weight 11. As illustrated in FIG. 4A, first and second comb-tooth-like fixed electrodes 17a, 17b, which respectively face the first and second movable electrodes 10a, 10b, are supported at one ends thereof by fixed unit anchors 19a, 19b. 
For example, the sensor chip 27 is fixed to a sensor package 29 with an adhesive 28, and the sensor package 29 is bonded onto a printed circuit board 31 with another adhesive 30 such as solder, as shown in FIG. 4B. The printed circuit board 31, on which the sensor chip 27 and so on has been mounted, is fixed to a vehicle at a predetermined position using a fixer such as a screw.
However, because the printed circuit board 31, the sensor package 29, the adhesives 28, 30, and the sensor chip 27 are different in linear expansion coefficient, a deformation such as a warp can be generated in the semiconductor substrate of the sensor chip 27. If the deformation is generated in the semiconductor substrate, the strain generated by the deformation is transmitted to the springs 12 through the movable unit anchors 14, which are connected to the semiconductor substrate.
As a result, the springs 12 resiliently deform in response to the strain to displace the movable electrodes 10a, 10b. Therefore, the electrode distances between the movable electrodes 10a, 10b and the fixed electrodes 17a, 17b vary to change the capacitances between the movable electrodes 10a, 10b and the fixed electrodes 17a, 17b. As a result, the thermal characteristics in offset voltage deteriorate.